Listen-before-talk (lbt) with new radio-spectrum sharing (nr-ss) discovery signal transmission

ABSTRACT

Wireless communications systems and methods related to performing spatial-specific listen-before-talk (LBT) with discovery signal transmissions for spectrum sharing are provided. A wireless communication device senses a channel in a spatial domain based on a plurality of expected beam transmission directions. The sensing includes sweeping through multiple directional reception beams and listening to the channel in a direction of each of the multiple directional reception beams. After the sensing, the wireless communication device transmits a channel reservation signal using an omnidirectional transmission beam and also transmits a plurality of discovery signals in one or more of the plurality of expected beam transmission directions during a discovery period to facilitate synchronization in the channel based on the sensing.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application for patent is a continuation of patentapplication Ser. No. 16/056,128 entitled, “LISTEN-BEFORE-TALK (LBT) WITHNEW RADIO-SPECTRUM SHARING (NR-SS) DISCOVERY SIGNAL TRANSMISSION,” filedAug. 6, 2018, and claims the benefit of U.S. Provisional Patent62/546,426, entitled, “LISTEN-BEFORE-TALK (LBT) WITH NEW RADIO-SPECTRUMSHARING (NR-SS) DISCOVERY SIGNAL TRANSMISSION,” filed Aug. 16, 2017, andassigned to the assignee hereof and hereby expressly incorporated byreference herein.

TECHNICAL FIELD

This application relates to wireless communication systems and methods,and more particularly to performing listen-before-talk (LBT) prior todiscovery signal transmissions in a frequency spectrum shared bymultiple network operating entities.

INTRODUCTION

Wireless communications systems are widely deployed to provide varioustypes of communication content such as voice, video, packet data,messaging, broadcast, and so on. These systems may be capable ofsupporting communication with multiple users by sharing the availablesystem resources (e.g., time, frequency, and power). A wirelessmultiple-access communications system may include a number of basestations (BSs), each simultaneously supporting communication formultiple communication devices, which may be otherwise known as userequipment (UE).

To meet the growing demands for expanded mobile broadband connectivity,wireless communication technologies are advancing from the LTEtechnology to a next generation new radio (NR) technology. NR mayprovision for dynamic medium sharing among network operators in alicensed spectrum, a shared spectrum, and/or an unlicensed spectrum. Forexample, shared spectrums and/or unlicensed spectrums may includefrequency bands at about 3.5 gigahertz (GHz), about 6 GHz, and about 60GHz.

In a radio access network such as an NR network, a base station maytransmit synchronization signals to allow UEs to search and acquiresynchronization to a cell within the radio access network. In someinstances, a base station may transmit synchronization signalsrepeatedly at a predetermined periodicity. When the network operates athigh frequencies, for example, at about 6 GHz or above 6 GHz, thepath-loss may be high. To overcome the high path-loss, a base stationmay perform beamforming, which may include analog and/or digitalbeamforming, to create narrow beams for transmissions to UEs in thenetwork. For example, the base station may transmit synchronizationsignals in different beam directions using narrow transmission beams.When the network operates in a shared medium or a shared channel, thesynchronization signal transmissions may collide with transmissions fromother nodes sharing the channel. One approach to avoiding collisions isto perform listen-before-talk (LBT) to ensure that the shared channel isclear before transmitting a synchronization signal. Since a base stationmay sweep through multiple narrow beams for synchronization signaltransmissions, LBT procedures considering beam sweeping are desirable.

BRIEF SUMMARY OF SOME EXAMPLES

The following summarizes some aspects of the present disclosure toprovide a basic understanding of the discussed technology. This summaryis not an extensive overview of all contemplated features of thedisclosure, and is intended neither to identify key or critical elementsof all aspects of the disclosure nor to delineate the scope of any orall aspects of the disclosure. Its sole purpose is to present someconcepts of one or more aspects of the disclosure in summary form as aprelude to the more detailed description that is presented later.

For example, in an aspect of the disclosure, a method of wirelesscommunication includes sensing, by a wireless communication device, achannel in a spatial domain based on a plurality of expected beamtransmission directions, wherein the wireless communication device isassociated with a first network operating entity, and wherein thechannel is shared by a plurality of network operating entities includingthe first network operating entity; and transmitting, by the wirelesscommunication device, a plurality of discovery signals in one or more ofthe plurality of expected beam transmission directions during adiscovery period to facilitate synchronization in the channel based onthe sensing.

In an additional aspect of the disclosure, an apparatus includes aprocessor configured to sense a channel in a spatial domain based on aplurality of expected beam transmission directions, wherein theapparatus is associated with a first network operating entity, andwherein the channel is shared by a plurality of network operatingentities including the first network operating entity; and a transceiverconfigured to transmit a plurality of discovery signals in one or moreof the plurality of expected beam transmission directions during adiscovery period to facilitate synchronization in the channel based onthe sensing.

In an additional aspect of the disclosure, a computer-readable mediumhaving program code recorded thereon, the program code includes code forcausing a wireless communication device to sense a channel in a spatialdomain based on a plurality of expected beam transmission directions,wherein the wireless communication device is associated with a firstnetwork operating entity, and wherein the channel is shared by aplurality of network operating entities including the first networkoperating entity; and code for causing the wireless communication deviceto transmit a plurality of discovery signals in one or more of theplurality of expected beam transmission directions during a discoveryperiod to facilitate synchronization in the channel based on thesensing.

Other aspects, features, and embodiments of the present invention willbecome apparent to those of ordinary skill in the art, upon reviewingthe following description of specific, exemplary embodiments of thepresent invention in conjunction with the accompanying figures. Whilefeatures of the present invention may be discussed relative to certainembodiments and figures below, all embodiments of the present inventioncan include one or more of the advantageous features discussed herein.In other words, while one or more embodiments may be discussed as havingcertain advantageous features, one or more of such features may also beused in accordance with the various embodiments of the inventiondiscussed herein. In similar fashion, while exemplary embodiments may bediscussed below as device, system, or method embodiments it should beunderstood that such exemplary embodiments can be implemented in variousdevices, systems, and methods.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a wireless communication network according toembodiments of the present disclosure.

FIG. 2 illustrates a discovery signal transmission scheme according toembodiments of the present disclosure.

FIG. 3 illustrates a discovery signal transmission scheme according toembodiments of the present disclosure.

FIG. 4 is a block diagram of an exemplary user equipment (UE) accordingto embodiments of the present disclosure.

FIG. 5 is a block diagram of an exemplary base station (BS) according toembodiments of the present disclosure.

FIG. 6 illustrates a discovery signal transmission scheme withomnidirectional listen-before-talk (LBT) according to embodiments of thepresent disclosure.

FIG. 7 illustrates a discovery signal transmission scheme withspatial-specific LBT according to embodiments of the present disclosure.

FIG. 8 illustrates a discovery signal transmission scheme withspatial-specific LBT according to embodiments of the present disclosure.

FIG. 9 illustrates a discovery signal transmission scheme withspatial-specific LBT according to embodiments of the present disclosure.

FIG. 10 illustrates a concurrent discovery signal and channelreservation signal transmission scheme according to embodiments of thepresent disclosure.

FIG. 11 is a flow diagram of a discovery signal communication methodaccording to embodiments of the present disclosure.

DETAILED DESCRIPTION

The detailed description set forth below, in connection with theappended drawings, is intended as a description of variousconfigurations and is not intended to represent the only configurationsin which the concepts described herein may be practiced. The detaileddescription includes specific details for the purpose of providing athorough understanding of the various concepts. However, it will beapparent to those skilled in the art that these concepts may bepracticed without these specific details. In some instances, well-knownstructures and components are shown in block diagram form in order toavoid obscuring such concepts.

The techniques described herein may be used for various wirelesscommunication networks such as code-division multiple access (CDMA),time-division multiple access (TDMA), frequency-division multiple access(FDMA), orthogonal frequency-division multiple access (OFDMA),single-carrier FDMA (SC-FDMA) and other networks. The terms “network”and “system” are often used interchangeably. A CDMA network mayimplement a radio technology such as Universal Terrestrial Radio Access(UTRA), cdma2000, etc. UTRA includes Wideband CDMA (WCDMA) and othervariants of CDMA. cdma2000 covers IS-2000, IS-95 and IS-856 standards. ATDMA network may implement a radio technology such as Global System forMobile Communications (GSM). An OFDMA network may implement a radiotechnology such as Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB),IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Flash-OFDMA, etc.UTRA and E-UTRA are part of Universal Mobile Telecommunication System(UMTS). 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) are newreleases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSMare described in documents from an organization named “3rd GenerationPartnership Project” (3GPP). CDMA2000 and UMB are described in documentsfrom an organization named “3rd Generation Partnership Project 2”(3GPP2). The techniques described herein may be used for the wirelessnetworks and radio technologies mentioned above as well as otherwireless networks and radio technologies, such as a next generation(e.g., 5^(th) Generation (5G) operating in mmWave bands) network.

To facilitate synchronization in a network, a base station (BS) maysweep through multiple narrow beams directing towards different beamdirections in a designated time period for transmitting discoverysignals. The designated time period may be referred to as a discoveryreference signal (DRS) measurement timing configuration (DMTC) period.The DMTC periods may be repeated at a predetermined periodicity. Thediscovery signals may be referred to as synchronization signal blocks(SSBs). An SSB may include a combination of synchronization signals,broadcast system information signals, and/or discovery referencesignals. In some instances, each SSB in a DMTC period may be transmittedin a different beam direction.

The present application describes mechanisms for performing LBT prior todiscovery signal transmissions in a frequency spectrum shared bymultiple network operating entities. For example, a BS may performomnidirectional LBT and/or spatial-specific LBTs to determine whether achannel is clear in beam directions where discovery signals are expectedto be transmitted in a subsequent time period. When the omnidirectionalLBT and/or the spatial-specific LBTs indicate that the channel is idle,the BS may proceed with the discovery signal transmissions. When theomnidirectional LBT and/or the spatial-specific LBTs indicate that thechannel is busy, the BS may refrain from proceeding with the discoverysignal transmissions.

In an embodiment, the BS may perform omnidirectional LBT prior to a DMTCperiod. For example, the BS may monitor the channel for a transmissionfrom another node using an omnidirectional reception beam. When thechannel is clear, the BS may additionally transmit a channel reservationsignal or a preamble signal using an omnidirectional transmission beamto indicate a reservation for the channel in a subsequent DMTC period.

In an embodiment, the BS may perform multiple spatial-specific ordirectional LBTs, sweeping through a set of narrow directional receptionbeams, prior to a DMTC period. For example, the BS may monitor thechannel in a beam direction covering a group of one or more expectedbeam transmission directions in a subsequent DMTC period in eachdirectional LBT. When the directional LBT indicates that the channel isclear, the BS may additionally transmit a channel reservation signal inthe monitored direction.

In an embodiment, the BS may perform multiple spatial-specific LBTs,sweeping through a set of directional beams, within a DMTC period. Forexample, the BS may monitor the channel in a beam direction covering agroup of one or more expected beam transmission directions in asubsequent sub-period within the DMTC period. When the directional LBTindicates that the channel is clear, the BS may additionally transmit achannel reservation signal in the monitored direction.

In an embodiment, the BS may transmit the discovery signals in a portionof a system frequency band. The BS may transmit a channel reservationsignal concurrent with a discovery signal using frequency-divisionmultiplexing (FDM) in the system frequency band. The BS may transmit adata signal on remaining resources in the DMTC period. The BS maytransmit the data signal in a beam direction based on monitored beamdirections.

Aspects of the present application can provide several benefits. Forexample, the omnidirectional LBT and the omnidirectional channelreservation can avoid interference from nearby transmitters with aminimal system overhead. The directional LBTs and the directionalchannel reservations can avoid interference from transmitters that usedirectional transmission beams and/or directional reception beams. Thus,the directional LBTs and the directional channel reservations canfurther improve system performance and reduce collisions. Performing thedirectional LBTs and the directional channel reservations within a DMTCperiod can reduce the time gap between a directional LBT andtransmissions in corresponding monitored beam directions. The reductionin the time gap can further improve system performance. The use of FDMfor transmitting channel reservation signals concurrent with discoverysignals can reduce system overhead. The use of unused resources withinthe DMTC period for data transmissions can improve system resourceutilization efficiency. The disclosed embodiments may be suitable foruse with any wireless communication protocol in any wireless network forspectrum sharing.

FIG. 1 illustrates a wireless communication network 100 according toembodiments of the present disclosure. The network 100 includes BSs 105,UEs 115, and a core network 130. In some embodiments, the network 100operates over a shared spectrum. The shared spectrum may be unlicensedor partially licensed to one or more network operators. Access to thespectrum may be limited and may be controlled by a separate coordinationentity. In some embodiments, the network 100 may be a LTE or LTE-Anetwork. In yet other embodiments, the network 100 may be a millimeterwave (mmW) network, a new radio (NR) network, a 5G network, or any othersuccessor network to LTE. The network 100 may be operated by more thanone network operator. Wireless resources may be partitioned andarbitrated among the different network operators for coordinatedcommunication between the network operators over the network 100.

The BSs 105 may wirelessly communicate with the UEs 115 via one or moreBS antennas. Each BS 105 may provide communication coverage for arespective geographic coverage area 110. In 3GPP, the term “cell” canrefer to this particular geographic coverage area of a BS and/or a BSsubsystem serving the coverage area, depending on the context in whichthe term is used. In this regard, a BS 105 may provide communicationcoverage for a macro cell, a pico cell, a femto cell, and/or other typesof cell. A macro cell generally covers a relatively large geographicarea (e.g., several kilometers in radius) and may allow unrestrictedaccess by UEs with service subscriptions with the network provider. Apico cell may generally cover a relatively smaller geographic area andmay allow unrestricted access by UEs with service subscriptions with thenetwork provider. A femto cell may also generally cover a relativelysmall geographic area (e.g., a home) and, in addition to unrestrictedaccess, may also provide restricted access by UEs having an associationwith the femto cell (e.g., UEs in a closed subscriber group (CSG), UEsfor users in the home, and the like). A BS for a macro cell may bereferred to as a macro BS. A BS for a pico cell may be referred to as apico BS. A BS for a femto cell may be referred to as a femto BS or ahome BS. In the example shown in FIG. 1, the BSs 105 a, 105 b and 105 care examples of macro BSs for the coverage areas 110 a, 110 b and 110 c,respectively. The BSs 105 d is an example of a pico BS or a femto BS forthe coverage area 110 d. As will be recognized, a BS 105 may support oneor multiple (e.g., two, three, four, and the like) cells.

Communication links 125 shown in the network 100 may include uplink (UL)transmissions from a UE 115 to a BS 105, or downlink (DL) transmissions,from a BS 105 to a UE 115. The UEs 115 may be dispersed throughout thenetwork 100, and each UE 115 may be stationary or mobile. A UE 115 mayalso be referred to as a mobile station, a subscriber station, a mobileunit, a subscriber unit, a wireless unit, a remote unit, a mobiledevice, a wireless device, a wireless communications device, a remotedevice, a mobile subscriber station, an access terminal, a mobileterminal, a wireless terminal, a remote terminal, a handset, a useragent, a mobile client, a client, or some other suitable terminology. AUE 115 may also be a cellular phone, a personal digital assistant (PDA),a wireless modem, a wireless communication device, a handheld device, atablet computer, a laptop computer, a cordless phone, a personalelectronic device, a handheld device, a personal computer, a wirelesslocal loop (WLL) station, an Internet of things (IoT) device, anInternet of Everything (IoE) device, a machine type communication (MTC)device, an appliance, an automobile, or the like.

The BSs 105 may communicate with the core network 130 and with oneanother. The core network 130 may provide user authentication, accessauthorization, tracking, Internet Protocol (IP) connectivity, and otheraccess, routing, or mobility functions. At least some of the BSs 105(e.g., which may be an example of an evolved NodeB (eNB), a nextgeneration NodeB (gNB), or an access node controller (ANC)) mayinterface with the core network 130 through backhaul links 132 (e.g.,S1, S2, etc.) and may perform radio configuration and scheduling forcommunication with the UEs 115. In various examples, the BSs 105 maycommunicate, either directly or indirectly (e.g., through core network130), with each other over backhaul links 134 (e.g., X1, X2, etc.),which may be wired or wireless communication links.

Each BS 105 may also communicate with a number of UEs 115 through anumber of other BSs 105, where the BS 105 may be an example of a smartradio head. In alternative configurations, various functions of each BS105 may be distributed across various BSs 105 (e.g., radio heads andaccess network controllers) or consolidated into a single BS 105.

In some implementations, the network 100 utilizes orthogonal frequencydivision multiplexing (OFDM) on the downlink and single-carrierfrequency division multiplexing (SC-FDM) on the UL. OFDM and SC-FDMpartition the system bandwidth into multiple (K) orthogonal subcarriers,which are also commonly referred to as tones, bins, or the like. Eachsubcarrier may be modulated with data. In general, modulation symbolsare sent in the frequency domain with OFDM and in the time domain withSC-FDM. The spacing between adjacent subcarriers may be fixed, and thetotal number of subcarriers (K) may be dependent on the systembandwidth. The system bandwidth may also be partitioned into subbands.

In an embodiment, the BSs 105 can assign or schedule transmissionresources (e.g., in the form of time-frequency resource blocks) for DLand UL transmissions in the network 100. DL refers to the transmissiondirection from a BS 105 to a UE 115, whereas UL refers to thetransmission direction from a UE 115 to a BS 105. The communication canbe in the form of radio frames. A radio frame may be divided into aplurality of subframes, for example, about 10. Each subframe can bedivided into slots, for example, about 2. Each slot may be furtherdivided into mini-slots. In a frequency-division duplexing (FDD) mode,simultaneous UL and DL transmissions may occur in different frequencybands. For example, each subframe includes a UL subframe in a ULfrequency band and a DL subframe in a DL frequency band. In atime-division duplexing (TDD) mode, UL and DL transmissions occur atdifferent time periods using the same frequency band. For example, asubset of the subframes (e.g., DL subframes) in a radio frame may beused for DL transmissions and another subset of the subframes (e.g., ULsubframes) in the radio frame may be used for UL transmissions.

The DL subframes and the UL subframes can be further divided intoseveral regions. For example, each DL or UL subframe may havepre-defined regions for transmissions of reference signals, controlinformation, and data. Reference signals are predetermined signals thatfacilitate the communications between the BSs 105 and the UEs 115. Forexample, a reference signal can have a particular pilot pattern orstructure, where pilot tones may span across an operational bandwidth orfrequency band, each positioned at a pre-defined time and a pre-definedfrequency. For example, a BS 105 may transmit cell specific referencesignals (CRSs) and/or channel state information-reference signals(CSI-RSs) to enable a UE 115 to estimate a DL channel. Similarly, a UE115 may transmit sounding reference signals (SRSs) to enable a BS 105 toestimate a UL channel. Control information may include resourceassignments and protocol controls. Data may include protocol data and/oroperational data. In some embodiments, the BSs 105 and the UEs 115 maycommunicate using self-contained subframes. A self-contained subframemay include a portion for DL communication and a portion for ULcommunication. A self-contained subframe can be DL-centric orUL-centric. A DL-centric subframe may include a longer duration for DLcommunication than UL communication. A UL-centric subframe may include alonger duration for UL communication than UL communication.

In an embodiment, a UE 115 attempting to access the network 100 mayperform an initial cell search by detecting a primary synchronizationsignal (PSS) from a BS 105. The PSS may enable synchronization of periodtiming and may indicate a physical layer identity value. The UE 115 maythen receive a secondary synchronization signal (SSS). The SSS mayenable radio frame synchronization, and may provide a cell identityvalue, which may be combined with the physical layer identity value toidentify the cell. The SSS may also enable detection of a duplexing modeand a cyclic prefix length. Some systems, such as TDD systems, maytransmit an SSS but not a PSS. Both the PSS and the SSS may be locatedin a central portion of a carrier, respectively.

After receiving the PSS and SSS, the UE 115 may receive a masterinformation block (MIB), which may be transmitted in the physicalbroadcast channel (PBCH). The MIB may contain system bandwidthinformation, a system frame number (SFN), and a Physical Hybrid-ARQIndicator Channel (PHICH) configuration. After decoding the MIB, the UE115 may receive one or more system information blocks (SIBs). Forexample, SIB1 may contain cell access parameters and schedulinginformation for other SIBs. Decoding SIB1 may enable the UE 115 toreceive SIB2. SIB2 may contain radio resource configuration (RRC)configuration information related to random access channel (RACH)procedures, paging, physical uplink control channel (PUCCH), physicaluplink shared channel (PUSCH), power control, SRS, and cell barring.After obtaining the MIB and/or the SIBs, the UE 115 can perform randomaccess procedures to establish a connection with the BS 105. Afterestablishing the connection, the UE 115 and the BS 105 can enter anormal operation stage, where operational data may be exchanged.

In an embodiment, the network 100 may operate over a shared channel,which may include a licensed spectrum, a shared spectrum, and/or anunlicensed spectrum, and may support dynamic medium sharing. The BSs 105and the UEs 115 may be operated by multiple network operating entitiessharing resources in the shared channel. A BS 105 or a UE 115 mayreserve a transmission opportunity (TXOP) in the shared channel bytransmitting a reservation signal prior to transmitting data in theTXOP. Other BSs 105 and/or other UEs 115 may listen to the channel andrefrain from accessing the channel during the TXOP upon detection of thereservation signal.

In an embodiment, the shared channel may be located at frequencies ofabout 6 GHz or above 6 GHz. When a BS 105 operates at a high-frequencyrange, the BSs 105 may communicate with the UEs 115 using narrowdirectional beams to overcome the high path-loss in the high-frequencyrange. For example, the BS 105 may transmit discovery signals, such asPSSs, SSSs, PBCH signals, and/or other discovery reference signals,using narrow directional beams. The BS 105 may sweep the narrowdirectional beams in multiple directions for the discovery signaltransmissions to allow UEs 115 located in different directions withrespect to the BS 105 to search and synchronize to the BS 105. In orderto avoid collisions with transmissions from other BSs 105 and/or otherUEs, the BS 105 may perform LBT in a spatial domain (e.g., spatial-awareLBT) prior to transmitting the discovery signals. Mechanisms forperforming LBT with discovery signal transmissions are described ingreater detail herein.

FIGS. 2 and 3 illustrate various mechanisms for transmitting discoverysignals in units of synchronization signal blocks (SSBs). Each SSB mayinclude a PSS, an SSS, a PBCH signal, and/or any discovery relatedreference signals. In FIGS. 2 and 3, the x-axes represent time in someconstant units, and the y-axes represent frequency in some constantunits.

FIG. 2 illustrates a discovery signal transmission scheme 200 accordingto embodiments of the present disclosure. The scheme 200 may be employedby BSs such as the BSs 105 in a network such as the network 100. Thescheme 200 illustrates a plurality of transmission slots 210 in afrequency band 208 over a duration 202. Each transmission slot 210includes a plurality of symbols 212. The frequency band 208 may belocated at frequencies of about sub-6 GHz or above 6 GHz. In someembodiments, the frequency band 208 may be in an unlicensed spectrum ora shared spectrum. A transmission slot 210 may correspond to a subframeor a slot within a subframe. A symbol 212 may correspond to an OFDMsymbol. A BS may communicate with a UE such as the UEs 115 in thetransmission slots 210. The BS may transmit SSBs 220 in one or more oftransmission slots 210 over the duration 202. The SSBs 220 may betransmitted over a frequency band 206. The transmissions are representedby pattern filled boxes. In an embodiment, the frequency band 208 maycorrespond to a system bandwidth of a network and the frequency band 206may have a substantially smaller bandwidth than the system bandwidth andmay be located within the frequency band 208. The transmissions of theSSBs 220 in the narrower frequency band 206 allow a UE to synchronize tothe network by operating in a smaller bandwidth than the systembandwidth, thereby reducing UE implementation complexity.

The duration 202 may be referred to as a DMTC window, which may includeany suitable amount of time. As an example, the duration 202 may beabout five milliseconds (ms). The number of transmission slots 210within the duration 202 may vary depending on the subcarrier spacing(SCS) and the number of symbols 212 within a transmission slot 210. Inan embodiment, each transmission slot 210 may include about fourteensymbols 212. When the SCS is about 15 kilohertz (kHz), each transmissionslot 210 may span about 1 ms and the duration 202 may include about fivetransmission slots 210. When the SCS is about 30 kHz, each transmissionslot 210 may span about 0.5 ms and the duration 202 may include aboutten transmission slots 210. When the SCS is about 120 kHz, eachtransmission slot 210 may span about 0.125 ms and the duration 202 mayinclude about forty transmission slots 210. When the SCS is about 240kHz, each transmission slot 210 may span about 62.5 microseconds (μs)and the duration 202 may include about eighty transmission slots 210.

In the scheme 200, a BS may transmit L number of SSBs 220 with theduration 202, where L is a positive integer. As an example, each SSB 220may span about four symbols 212. Thus, each transmission slot 210 mayinclude a maximum of about two SSBs 220. As shown, a SSB 220 a may betransmitted in the third, fourth, fifth, sixth symbols 212 of atransmission slot 210 and another SSB 220 b may transmitted in theninth, tenth, eleventh, and twelve symbols 212 of the transmission slot210. In some other embodiments, the two SSBs 220 a and 220 b may betransmitted during other symbols 212 within the transmission slot 210. Lmay have a value of about 4, 8, or 64 depending on the SCS and theduration 202. In an embodiment, L may be about 4 or 8 for a SCS of about15 kHz or about 30 kHz. When L is 4, a BS may transmit four SSBs 220 intwo transmission slots 210 within the duration 202. In some instances,the BS may transmit the SSBs 220 in consecutive transmission slots 210.When L is 8, a BS may transmit eight SSBs 220 in four transmission slots210 (e.g., consecutively) within the duration 202.

In an embodiment, L may be about 64 for a SCS of about 120 kHz or about240 kHz. Thus, a BS may transmit sixty-four SSBs 220 in about thirty-twotransmission slots 210 within the duration 202. In some instances, theBS may transmit the SSBs 220 in groups of eight SSBs 220 over fourtransmission slots 210 and the groups may be separated by onetransmission slot 210.

In an embodiment, a BS may transmit SSBs 220 in different beamdirections over the duration 202. For example, the BS may include anarray of antenna elements and may configure the array of antennaelements to form a transmission beam 211 in a certain direction. As anexample, the BS may transmit the SSB 220 a over a transmission beam 211a (e.g., shown as pattern-filled) directing towards a direction 216 andmay transmit the SSB 220 b over another transmission beam 211 b (e.g.,shown as pattern-filled) directing towards a direction 214. In someinstances, the duration 202 or the DMTC window may be repeated at apredetermined periodicity (e.g., at about 40 ms, about 80 ms, or about100 ms), where a BS may periodically transmit the SSBs 220.

FIG. 3 illustrates a discovery signal transmission scheme 300 accordingto embodiments of the present disclosure. The scheme 300 may be employedby BSs such as the BSs 105 in a network such as the network 100. Thescheme 300 may have a substantially similar transmission slotconfiguration as in the scheme 200. However, the scheme 300 may employdifferent SCSs for data transmissions and discovery signal or SSBtransmissions. As an example, a network may employ an SCS of about 120kHz for data transmissions and an SCS of about 240 kHz for SSBtransmissions. Similar to the scheme 200, a transmission slot 210 mayinclude about fourteen symbols 212. However, a BS may transmit a maximumof about four SSBs 320 similar to the SSBs 220 in a transmission slot210. Each SSB 320 may span about two symbols 212 instead of four symbols212 due to the larger SCS used for SSB transmissions. Similar to thescheme 200, each SSB 320 may be transmitted in a different beamdirection. As shown, a BS may sweep through multiple narrow directionaltransmissions beams 211 a, 211 b, 211 c, and 211 d during a transmissionslot 210 for transmitting the SSBs 320 a, 320 b, 320 c, and 320 d,respectively.

FIG. 4 is a block diagram of an exemplary UE 400 according toembodiments of the present disclosure. The UE 400 may be a UE 115 asdiscussed above. As shown, the UE 400 may include a processor 402, amemory 404, a communication discovery module 408, a transceiver 410including a modem subsystem 412 and a radio frequency (RF) unit 414, andone or more antennas 416. These elements may be in direct or indirectcommunication with each other, for example via one or more buses.

The processor 402 may include a central processing unit (CPU), a digitalsignal processor (DSP), an application specific integrated circuit(ASIC), a controller, a field programmable gate array (FPGA) device,another hardware device, a firmware device, or any combination thereofconfigured to perform the operations described herein. The processor 402may also be implemented as a combination of computing devices, e.g., acombination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration.

The memory 404 may include a cache memory (e.g., a cache memory of theprocessor 402), random access memory (RAM), magnetoresistive RAM (MRAM),read-only memory (ROM), programmable read-only memory (PROM), erasableprogrammable read only memory (EPROM), electrically erasableprogrammable read only memory (EEPROM), flash memory, solid state memorydevice, hard disk drives, other forms of volatile and non-volatilememory, or a combination of different types of memory. In an embodiment,the memory 404 includes a non-transitory computer-readable medium. Thememory 404 may store instructions 406. The instructions 406 may includeinstructions that, when executed by the processor 402, cause theprocessor 402 to perform the operations described herein with referenceto the UEs 115 in connection with embodiments of the present disclosure.Instructions 406 may also be referred to as code. The terms“instructions” and “code” should be interpreted broadly to include anytype of computer-readable statement(s). For example, the terms“instructions” and “code” may refer to one or more programs, routines,sub-routines, functions, procedures, etc. “Instructions” and “code” mayinclude a single computer-readable statement or many computer-readablestatements.

The communication discovery module 408 may be implemented via hardware,software, or combinations thereof. For example, the communicationdiscovery module 408 may be implemented as a processor, circuit, and/orinstructions 406 stored in the memory 404 and executed by the processor402. The communication discovery module 408 may be used for variousaspects of the present disclosure. For example, the communicationdiscovery module 408 is configured to receive discovery signals (e.g.,PSS, SSSs, PBCH signals, discovery reference signals, and SSBs 220 and320) from a BS such as the BSs 105 a over a shared channel (e.g., thefrequency band 208), synchronize to the BS based on the discoverysignals, and/or communicate with the BS after synchronization, asdescribed in greater detail herein.

As shown, the transceiver 410 may include the modem subsystem 412 andthe RF unit 414. The transceiver 410 can be configured to communicatebi-directionally with other devices, such as the BSs 105. The modemsubsystem 412 may be configured to modulate and/or encode the data fromthe memory 404, and/or the communication discovery module 408 accordingto a modulation and coding scheme (MCS), e.g., a low-density paritycheck (LDPC) coding scheme, a turbo coding scheme, a convolutionalcoding scheme, a digital beamforming scheme, etc. The RF unit 414 may beconfigured to process (e.g., perform analog to digital conversion ordigital to analog conversion, etc.) modulated/encoded data from themodem subsystem 412 (on outbound transmissions) or of transmissionsoriginating from another source such as a UE 115 or a BS 105. The RFunit 414 may be further configured to perform analog beamforming inconjunction with the digital beamforming. Although shown as integratedtogether in transceiver 410, the modem subsystem 412 and the RF unit 414may be separate devices that are coupled together at the UE 115 toenable the UE 115 to communicate with other devices.

The RF unit 414 may provide the modulated and/or processed data, e.g.data packets (or, more generally, data messages that may contain one ormore data packets and other information), to the antennas 416 fortransmission to one or more other devices. This may include, forexample, transmission of random access signals for initial networkattachment and/or data signals carrying information data according toembodiments of the present disclosure. The antennas 416 may furtherreceive data messages transmitted from other devices. This may include,for example, reception of discovery signals such as PSSs, SSSs, PBCHsignals, discovery reference signals, and/or SSBs according toembodiments of the present disclosure. The antennas 416 may provide thereceived data messages for processing and/or demodulation at thetransceiver 410. The antennas 416 may include multiple antennas ofsimilar or different designs in order to sustain multiple transmissionlinks. The RF unit 414 may configure the antennas 416.

FIG. 5 is a block diagram of an exemplary BS 500 according toembodiments of the present disclosure. The BS 500 may be a BS 105 asdiscussed above. A shown, the BS 500 may include a processor 502, amemory 504, a communication discovery module 508, a transceiver 510including a modem subsystem 512 and a RF unit 514, and one or moreantennas 516. These elements may be in direct or indirect communicationwith each other, for example via one or more buses.

The processor 502 may have various features as a specific-typeprocessor. For example, these may include a CPU, a DSP, an ASIC, acontroller, a FPGA device, another hardware device, a firmware device,or any combination thereof configured to perform the operationsdescribed herein. The processor 502 may also be implemented as acombination of computing devices, e.g., a combination of a DSP and amicroprocessor, a plurality of microprocessors, one or moremicroprocessors in conjunction with a DSP core, or any other suchconfiguration.

The memory 504 may include a cache memory (e.g., a cache memory of theprocessor 502), RAM, MRAM, ROM, PROM, EPROM, EEPROM, flash memory, asolid state memory device, one or more hard disk drives, memristor-basedarrays, other forms of volatile and non-volatile memory, or acombination of different types of memory. In some embodiments, thememory 504 may include a non-transitory computer-readable medium. Thememory 504 may store instructions 506. The instructions 506 may includeinstructions that, when executed by the processor 502, cause theprocessor 502 to perform operations described herein. Instructions 506may also be referred to as code, which may be interpreted broadly toinclude any type of computer-readable statement(s) as discussed abovewith respect to FIG. 5.

The communication discovery module 508 may be implemented via hardware,software, or combinations thereof. For example, the communicationdiscovery module 508 may be implemented as a processor, circuit, and/orinstructions 506 stored in the memory 504 and executed by the processor502. The communication discovery module 508 may be used for variousaspects of the present disclosure. For example, the communicationdiscovery module 508 is configured to perform spatial-aware ordirectional LBT in a shared channel (e.g., the frequency band 208),transmit discovery signals (e.g., SSBs 220 and 320) based on the resultsof the LBT, and/or transmit channel reservation signals or preamblesignals to silence other nearby transmitters that may interfere withdiscovery signal transmission, as described in greater detail herein.

As shown, the transceiver 510 may include the modem subsystem 512 andthe RF unit 514. The transceiver 510 can be configured to communicatebi-directionally with other devices, such as the UEs 115 and/or anothercore network element. The modem subsystem 512 may be configured tomodulate and/or encode data according to a MCS, e.g., a LDPC codingscheme, a turbo coding scheme, a convolutional coding scheme, a digitalbeamforming scheme, etc. The RF unit 514 may be configured to process(e.g., perform analog to digital conversion or digital to analogconversion, etc.) modulated/encoded data from the modem subsystem 512(on outbound transmissions) or of transmissions originating from anothersource such as a UE 115 or 400. The RF unit 514 may be furtherconfigured to perform analog beamforming and/or digital beamforming fordirectional signal transmissions and/or receptions. In some embodiments,the transceiver 510 may include antenna array elements and/ortransceiver components (e.g., power amplifiers) that can be switched onor off to form a beam in a particular direction. Alternatively, thetransceiver 510 may include multiple transmit/receive chains and mayswitch between the multiple transmit/receive chains to form a beam in aparticular direction. Although shown as integrated together intransceiver 510, the modem subsystem 512 and the RF unit 514 may beseparate devices that are coupled together at the BS 105 to enable theBS 105 to communicate with other devices.

The RF unit 514 may provide the modulated and/or processed data, e.g.data packets (or, more generally, data messages that may contain one ormore data packets and other information), to the antennas 516 fortransmission to one or more other devices. This may include, forexample, transmission of information to complete attachment to a networkand communication with a camped UE 115 or 400 according to embodimentsof the present disclosure. The antennas 516 may further receive datamessages transmitted from other devices and provide the received datamessages for processing and/or demodulation at the transceiver 510. Theantennas 516 may include multiple antennas of similar or differentdesigns in order to sustain multiple transmission links.

FIGS. 6-10 illustrate various mechanisms for performing spatial-aware ordirectional LBTs in a shared channel prior to transmitting discoverysignals (e.g., PSSs, SSSs, PBCH signals, discovery reference signals,and/or SSBs 220 and 320). In FIGS. 6-10, the x-axes represent time insome constant units, and the y-axes represent frequency in some constantunits.

FIG. 6 illustrates a discovery signal transmission scheme 600 withomnidirectional LBT according to embodiments of the present disclosure.The scheme 600 may be employed by BSs such as the BSs 105 and 500 in anetwork such as the network 100. The scheme 600 includes a DMTC period602 including a plurality of transmission slots 610 in a frequency band608 shared by multiple network operating entities. The transmissionslots 610 are shown as 610 _(S(1)) to 610 _(S(N)). Each transmissionslot 610 includes a plurality of symbols 612. The DMTC period 602, thetransmission slots 610, the symbols 612, and the frequency band 608 maybe substantially similar to the duration 202, the transmission slots210, the symbols 212, and the frequency band 208, respectively. The DMTCperiod 602 may be repeated at a sparse frequency rate, for example, atabout every 80 ms, every 100 ms, or any suitable rate.

Similar to the schemes 200 and 300, a BS may transmit a plurality ofSSBs 620 in a frequency band 606 within the frequency band 608 usingmultiple directional transmission beams 611 directing towards differentbeam directions during the DMTC period 602. The frequency band 606 maybe substantially similar to the frequency band 206. The directiontransmission beams 611 may be substantially similar to the directiontransmission beams 211. For example, the BS may transmit a subset of theSSBs 620 in the transmission slot 610 _(S(1)) and another subset of theSSBs 620 in the transmission slot 610 s(N). In the transmission slot 610_(S(1)), the SSBs 620 a, 620 b, 620 c, and 620 d may be transmitted overdifferent transmission beams 611 a, 611 b, 611 c, and 611 d,respectively, each directing towards a different direction. Similarly,in the transmission slot 610 s(N), the SSBs 620 e, 620 f, 620 g, and 620h may be transmitted over different transmission beams 611 e, 611 f, 611g, and 611 h, respectively, each directing towards a differentdirection. The SSBs 620 may be substantially similar to the SSBs 220 and320. For example, each SSB 620 may include a PSS, a SSS, a PBCH signal,and/or a discovery reference signal, as described in greater detailherein.

To avoid collisions with transmissions from other nodes (e.g., the BSs105 and the UEs 115) in the frequency band 208, the BS may listen to thechannel (e.g., the frequency band 608) prior to transmitting the SSBs620. For example, the BS may perform omnidirectional LBT 630 in a period604 prior to the DMTC period 602. The BS may configure antenna arrayelements (e.g., in the transceiver 510) such that the BS may receivesignals in all available directions as shown by the omnidirectionalreception beam 614. When the BS detects a transmission from another node(e.g., a BS 105 or a UE 115) in the channel from any direction, the BSmay refrain from proceeding with the transmissions of the SSBs 620during the DMTC period 602. The detection may be based on energydetection and/or sequence (e.g., a predetermined waveform used forchannel reservation) detection and/or preamble (e.g., a predeterminedwaveform transmitted along with a packet) detection. However, when theBS determines that the channel is idle, the BS may continue to transmitthe SSBs 620 during the DMTC period 602.

The BS may optionally transmit a channel reservation signal 640 afterperforming the omnidirectional LBT 630 to avoid interference from nearbytransmitters. The BS may transmit the channel reservation signal 640over an omnidirectional transmission beam in a period 605. The period605 may follow the period 604 without a time gap since the BS is notrequired to switch a beam direction between the omnidirectional LBT 630and the omnidirectional transmission of the channel reservation signal640. The BS may configure the antenna array elements to transmit in alldirections, as shown by the omnidirectional transmission beam 613. Thechannel reservation signal 640 may include a predetermined preamblesequence. When another transmitter detected the channel reservationsignal 640, the transmitter may refrain from transmitting in thefrequency band 608.

The scheme 600 may avoid interferers that are substantially close to theBS. However, the omnidirectional LBT 630 may not be effective indetecting energy or a preamble transmission from a specific beamdirection and the omnidirectional channel reservation may not be heardby a node listening or sensing the channel in a specific beam direction.

FIG. 7 illustrates a discovery signal transmission scheme 700 withspatial-specific LBT according to embodiments of the present disclosure.The scheme 700 may be employed by BSs such as the BSs 105 and 500 in anetwork such as the network 100. The scheme 700 may be substantiallysimilar to the scheme 600. However, the scheme 700 may performspatial-specific LBT and spatial-specific channel reservation inaddition to omnidirectional LBT and omnidirectional channel reservation.As shown, a BS may perform spatial-specific LBT 710 by sweeping througha plurality of directional reception beams 712 in a period 702 prior tothe DMTC period 602. For example, the BS may perform K number ofspatial-specific LBTs 710 as shown by 710 _(B(1)) to 710B_(B(K)). Eachreception beam 712 may have a coverage over one or more of thetransmission beams 611 used for transmitting the SSBs 620 during theDMTC period 602. In other words, the receive beams 712 may have a widerbeam width than the transmission beams 611. As an example, a BS mayconfigure antenna array elements to form a reception beam 712 _(B(1))for sensing the channel (e.g., the frequency band) in the beamdirections of the transmission beams 611 a, 611 b, 611 c, and 611 d.

When a spatial-specific LBT 710 indicates that the channel is clear, theBS may proceed with transmissions of SSBs 620 in the beam directionscorresponding to the spatial-specific LBT 710. Conversely, when aspatial-specific LBT 710 indicates that the channel is occupied, the BSmay refrain from transmitting SSBs 620 in the beam directionscorresponding to the spatial-specific LBT 710.

Similar to the scheme 600, the BS may optionally transmit a channelreservation signal 720 after performing each spatial-specific LBT 710.The channel reservation signal 720 may be substantially similar to thechannel reservation signals 640. But, the channel reservation signal 720may be transmitted using a directional beam 713. As shown, the channelreservation signals 720 are transmitted in the same beam direction as aprior spatial-specific LBT 710.

The spatial-specific LBTs and the spatial-specific channel reservationsmay be effective in avoiding interferers transmitting and/or listeningin specific spatial directions. Thus, the scheme 700 may further reducecollisions compared to the scheme 600. However, the BS may require atime gap 704 for switching from one beam direction to another beamdirection between the spatial-specific LBTs 710. The presence of thetime gap 704 may lead to a collision from an interferer beginning atransmission within the time gap 704.

FIG. 8 illustrates a discovery signal transmission scheme 800 withspatial-specific LBT according to embodiments of the present disclosure.The scheme 800 may be employed by BSs such as the BSs 105 and 500 in anetwork such as the network 100. The scheme 800 may be substantiallysimilar to the scheme 700. However, a BS may sweep spatial-specific LBTs710 in all K directions prior to transmitting spatial-specific channelreservations signals 720 in response to the spatial-specific LBTs 710.The spatial-specific LBTs 710 and the transmissions of thespatial-specific channel reservations signals 720 may be performedwithin a period 802 prior to the DMTC period 602. A time gap similar tothe time gap 704 may be required between each spatial-specific LBT 710and each spatial-specific channel reservation signal 720 transmissionsto allow the BS to switch antenna array configurations.

FIG. 9 illustrates a discovery signal transmission scheme 900 withspatial-specific LBT according to embodiments of the present disclosure.The scheme 900 may be employed by BSs such as the BSs 105 and 500 in anetwork such as the network 100. The scheme 900 may be substantiallysimilar to the schemes 700 and 800. However, in the scheme 900, a BS mayperform spatial-specific LBTs 710 and transmit spatial-specific channelreservation signals 720 within a DMTC period 602 instead of prior to aDMTC period 602.

The BS may perform a spatial-specific LBT 710 prior to transmitting asubset of one or more SSBs 620. The spatial-specific LBT 710 may beperformed based on the expected beam transmission directions used fortransmitting the subset of SSBs 620. As an example, the BS may perform aspatial-specific LBT 710 _(B(1)) using a directional reception beam 712_(B(1)) prior to transmitting the SSBs 620 a, 620 b, 620 c, and 620 d.The directional reception beam 712 _(B(1)) may include a coverage overthe transmission beams 611 a, 611 b, 611 c, and 611 d. The BS mayoptionally transmit a channel reservation signal 720 in response to eachspatial-specific LBT 710 by using the same beam direction as thespatial-specific LBT 710. The BS may perform the spatial-specific LBT710 and transmit the spatial-specific channel reservation signal 720transmission immediately before the transmission of the first SSB 620 ain the subset, for example, in a period of one to two symbols 612.

When a spatial-specific LBT 710 (e.g., the spatial-specific LBT 710_(B(1))) indicates that the channel is clear, the BS may proceed withtransmitting SSBs 620 (e.g., the SSBs 620 a, 620 b, 620 c, and 620 d) inthe beam directions corresponding to the spatial-specific LBT 710.Conversely, when a spatial-specific LBT 710 (e.g., the spatial-specificLBT 710 _(B(K))) indicates that the channel is occupied, the BS mayrefrain from transmitting SSBs 620 in the beam directions correspondingto the spatial-specific LBT 710 as shown by the dashed box with thecross.

Comparing the scheme 900 to the schemes 700 and 800, the scheme 900 mayfurther reduce collisions. In addition, the scheme 900 may allow thechannel reservation signals 720 to be multiplexed with the SSBs 620, asdescribed in greater detail herein.

While the schemes 700-900 are illustrated with omnidirectional LBT andomnidirectional channel reservation transmissions in conjunctions withspatial-specific LBTs and spatial-specific channel reservations, theomnidirectional LBT and the omnidirectional channel reservationtransmissions may be optional.

FIG. 10 illustrates a discovery signal transmission scheme 1000 withconcurrent channel reservation signal transmission according toembodiments of the present disclosure. The scheme 1000 may be employedby BSs such as the BSs 105 and 500 in a network such as the network 100.In particular, the scheme 1000 may be used in conjunction with thescheme 900 to transmit a channel reservation signal 1010 using FDM inplace of the channel reservation signal 720 (e.g., using TDM). Forexample, a BS may transmit an SSB 620 including a PSS 1022, an SSS 1026,and PBCH signals 1024 in the frequency band 606 and may transmit achannel reservation signal 1010 in the same symbol as the PSS 1022 usingremaining unused resources (e.g., resource elements (REs)) in thefrequency portion 1006. The channel reservation signal 1010 may includea predetermined preamble sequence configured based on the number ofunused resource elements in the frequency portion 1006. In addition, theBS may transmit a demodulation reference signal (DMRS) 1030 distributedin the frequency portion 1006 to facilitate decoding of the PBCH signals1024, channel discovery, and/or channel synchronization. Since thechannel reservation signal 1010 is frequency multiplexed with the SSB620, the scheme 1000 may reduce system overhead compared to the scheme900.

As shown in the scheme 900 and 1000, there are unused resources (e.g.,time-frequency resources) in the DMTC period 602. For example, thefirst, second, third, fourth, thirteen, and fourteen symbols 612 in thetransmission slot 610 _(S(1)) are unused. Thus, a BS may transmit a datasignal in the unused symbols 612. In an embodiment, the BS may transmitthe data signal in a beam direction corresponding to a spatial-specificLBT 710 performed for the subset of SSBs 620 in the transmission slot610 _(S(1)). For example, the BS may use a directional transmission beamsimilar to the transmission beam 711 _(B(1)), which may be wider thanthe transmission beams 611 a, 611 b, 611 c, and 611 d, for the datasignal transmission. Alternatively, the BS may select a directionaltransmission beam from any one of the transmission beams 611 a, 611 b,611 c, and 611 d. The BS may also transmit the data signal in the samesymbol 612 as an SSB 620 using remaining unused frequency resources(e.g., in the frequency portion 1006) and in the same beam direction asthe SSB 620. Thus, the BS may multiplex data signals with the SSBs 620in a transmission slot 610 in a time domain and/or frequency domain.

FIG. 11 is a flow diagram of a communication discovery method 1100according to embodiments of the present disclosure. Steps of the method1100 can be executed by a computing device (e.g., a processor,processing circuit, and/or other suitable component) of a wirelesscommunication device, such as the BSs 105 and 500. The method 1100 mayemploy similar mechanisms as in the schemes 200, 300, 600, 700, 800,900, and 1000 as described with respect to FIGS. 2, 3, 6, 7, 8, 9, and10, respectively. As illustrated, the method 1100 includes a number ofenumerated steps, but embodiments of the method 1100 may includeadditional steps before, after, and in between the enumerated steps. Insome embodiments, one or more of the enumerated steps may be omitted orperformed in a different order.

At step 1110, the method 1100 includes sensing, by a wirelesscommunication device, a channel (e.g., the frequency bands 208 and 608)in a spatial domain based on a plurality of expected beam transmissiondirections (e.g., based on the transmission beams 211 and 611). Thewireless communication device may be associated with a first networkoperating entity. The channel may be shared by a plurality of networkoperating entity including the first network operating entity.

At step 1120, the method 1100 includes transmitting, by the wirelesscommunication device, a plurality of discovery signals (e.g., the SSBs220 and 620, the PSS 1022, the SSS 1026, the PBCH signals 1024, and/orany discovery reference signal) in one or more of the plurality ofexpected beam transmission directions during a discovery period (e.g.,the DMTC period 602) to facilitate synchronization in the channel basedon the sensing.

In an embodiment, the sensing includes monitoring the channel for atransmission from another wireless communication device using anomnidirectional reception beam (e.g., the omnidirectional reception beam614) before the discovery period. In response to the sensing, thewireless communication device may transmit a channel reservation signal(e.g., the channel reservation signal 640) over an omnidirectionaltransmission beam (e.g., the omnidirectional transmission beam 613)before the discovery period.

In an embodiment, the sensing includes sweeping through multiple narrowdirectional reception beams (e.g., the reception beams 712) andlistening to the channel in each of the beam directions. For example,the sensing includes monitoring the channel in a first subset of theplurality of expected beam transmission directions (e.g., the beamdirections of the beams 611 a, 611 b, 611 c, and 611 d) for atransmission from another wireless communication device. The monitoringincludes configuring antenna elements (e.g., in the transceiver 510) ofthe wireless communication device to direct reception in a beamdirection including a coverage over the first subset of the plurality ofexpected beam transmission directions. In such an embodiment, thetransmitting of the plurality of discovery signals may includetransmitting a subset of the plurality of discovery signals (e.g., theSSBs 620 a, 620 b, 620 c, and 620 d), each in one of the first subset ofthe plurality of expected beam transmission directions. The sensing canfurther include monitoring the channel in a second subset of theplurality of expected beam transmission directions (e.g., based on thebeams 611 e, 611 f, 611 g, and 611 h) for a transmission from anotherwireless communication device. The sensing can be repeated in subsets ofthe expected beam transmission directions until all beam directions aremonitored.

In some embodiments, the directional sensing (e.g., using the narrowbeams) may be performed prior to the discovery period, for example, asshown in the schemes 700 and 800. In response to the sensing, thewireless communication device may transmit a channel reservation signal(e.g., the channel reservation signal 720) after sensing each beamdirection before switching to another beam direction. Each channelreservation signal may be transmitted in the same direction as thesensing. Alternatively, the wireless communication device may sweepthrough all the subset of beam directions for sensing before sweepingthrough the subset of beam directions for transmitting the channelreservation signals.

In some embodiments, the directional sensing may be performed within thediscovery period, for example, as shown in the scheme 900. For example,the channel is monitored in the first subset of the plurality ofexpected beam transmission directions within the discovery period beforetransmitting the subset of the plurality of discovery signals. Inresponse to the sensing, the wireless communication device may transmita channel reservation signal in the same direction as the sensing beforetransmitting the subset of discovery signals. In some embodiments, thewireless communication device can transmit the channel reservationsignal concurrent with at least one of the subset of discovery signalsusing FDM, for example, as shown in the scheme 1000. In someembodiments, the monitoring in the second subset of the plurality ofexpected beam transmission directions may detect a transmission fromanother wireless communication device. Upon the detection, the wirelesscommunication device may refrain from transmitting discovery signals inthe second subset of the plurality of expected beam transmissiondirections.

Information and signals may be represented using any of a variety ofdifferent technologies and techniques. For example, data, instructions,commands, information, signals, bits, symbols, and chips that may bereferenced throughout the above description may be represented byvoltages, currents, electromagnetic waves, magnetic fields or particles,optical fields or particles, or any combination thereof.

The various illustrative blocks and modules described in connection withthe disclosure herein may be implemented or performed with ageneral-purpose processor, a DSP, an ASIC, an FPGA or other programmablelogic device, discrete gate or transistor logic, discrete hardwarecomponents, or any combination thereof designed to perform the functionsdescribed herein. A general-purpose processor may be a microprocessor,but in the alternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices (e.g., a combinationof a DSP and a microprocessor, multiple microprocessors, one or moremicroprocessors in conjunction with a DSP core, or any other suchconfiguration).

Further embodiments of the present disclosure include a method ofwireless communication, comprising sensing, by a wireless communicationdevice, a channel in a spatial domain based on a plurality of expectedbeam transmission directions, wherein the wireless communication deviceis associated with a first network operating entity, and wherein thechannel is shared by a plurality of network operating entities includingthe first network operating entity; and transmitting, by the wirelesscommunication device, a plurality of discovery signals in one or more ofthe plurality of expected beam transmission directions during adiscovery period to facilitate synchronization in the channel based onthe sensing.

In some embodiments, wherein the sensing includes monitoring the channelfor a transmission from another wireless communication device using anomnidirectional reception beam before the discovery period. In someembodiments, the method further comprises transmitting, by the wirelesscommunication device, a channel reservation signal using anomnidirectional transmission beam before the discovery period based onthe sensing. In some embodiments, wherein the sensing includesmonitoring the channel in a first subset of the plurality of expectedbeam transmission directions for a transmission from another wirelesscommunication device. In some embodiments, wherein the monitoringincludes configuring antenna elements of the wireless communicationdevice to direct reception in a beam direction including a coverage overthe first subset of the plurality of expected beam transmissiondirections. In some embodiments, wherein the transmitting includestransmitting, a subset of the plurality of discovery signals, each inone of the first subset of the plurality of expected beam transmissiondirections. In some embodiments, wherein the sensing further includesmonitoring the channel in a second subset of the plurality of expectedbeam transmission directions for a transmission from another wirelesscommunication device, wherein the first subset and the second subset ofthe plurality of expected beam transmission directions are different,and wherein the channel is monitored in the first subset of theplurality of expected beam transmission directions and in the secondsubset of the plurality of expected beam transmission directions beforethe discovery period. In some embodiments, the method further comprisestransmitting, by the wireless communication device, a first channelreservation signal in the first subset of the plurality of expected beamtransmission directions based on the monitoring in the first subset ofthe plurality of expected beam transmission directions; andtransmitting, by the wireless communication device, a second channelreservation signal in the second subset of the plurality of expectedbeam transmission directions based on the monitoring in the secondsubset of the plurality of expected beam transmission directions. Insome embodiments, wherein the channel is monitored in the first subsetof the plurality of expected beam transmission directions within thediscovery period before transmitting the subset of the plurality ofdiscovery signals. In some embodiments, the method further comprisestransmitting, by the wireless communication device, a channelreservation signal in the first subset of the plurality of expected beamtransmission directions before transmitting the subset of the pluralityof discovery signals based on the monitoring in first subset of theplurality of expected beam transmission directions. In some embodiments,the method further comprises transmitting, by the wireless communicationdevice, a channel reservation signal concurrent with one of the subsetof the plurality of discovery signals based on frequency-divisionmultiplexing (FDM). In some embodiments, wherein the sensing includesmonitoring the channel in a second subset of the plurality of expectedbeam transmission directions within the discovery period; and detectinga transmission from another wireless communication device over thechannel in the second subset of the plurality of expected beamtransmission directions, and wherein the method further comprisesrefraining, by the wireless communication device, from transmittingdiscovery signals in the second subset of the plurality of expected beamtransmission directions based on the detecting. In some embodiments, themethod further comprises transmitting a data signal by multiplexing thedata signal with one or more of the subset of the plurality of discoverysignals in at least one of a frequency domain or a time domain. In someembodiments, wherein the data signal is transmitted in at least one ofthe first subset of the plurality of expected beam transmissiondirections. In some embodiments, wherein each of the plurality ofdiscovery signals includes at least one of a primary synchronizationsignal (PSS), a secondary synchronization signal (SSS), a physicalbroadcast channel (PBCH) signal, or a discovery reference signal.

Further embodiments of the present disclosure include an apparatuscomprising a processor configured to sense a channel in a spatial domainbased on a plurality of expected beam transmission directions, whereinthe apparatus is associated with a first network operating entity, andwherein the channel is shared by a plurality of network operatingentities including the first network operating entity; and a transceiverconfigured to transmit a plurality of discovery signals in one or moreof the plurality of expected beam transmission directions during adiscovery period to facilitate synchronization in the channel based onthe sensing.

In some embodiments, wherein the processor is further configured tosense the channel by monitoring the channel for a transmission fromanother wireless communication device using an omnidirectional receptionbeam before the discovery period. In some embodiments, wherein thetransceiver is further configured to transmit a channel reservationsignal using an omnidirectional transmission beam before the discoveryperiod based on the sensing. In some embodiments, wherein the processoris further configured to sense the channel by monitoring the channel ina first subset of the plurality of expected beam transmission directionsfor a transmission from another wireless communication device. In someembodiments, wherein the processor is further configured to monitor thechannel by configuring antenna elements of the wireless communicationdevice to direct reception in a beam direction including a coverage overthe first subset of the plurality of expected beam transmissiondirections. In some embodiments, wherein the transceiver is furtherconfigured to transmit plurality of discovery signals by transmitting asubset of the plurality of discovery signals, each in one of the firstsubset of the plurality of expected beam transmission directions. Insome embodiments, wherein the processor is further configured to sensethe channel by monitoring the channel in a second subset of theplurality of expected beam transmission directions for a transmissionfrom another wireless communication device, wherein the first subset andthe second subset of the plurality of expected beam transmissiondirections are different, and wherein the channel is monitored in thefirst subset of the plurality of expected beam transmission directionsand in the second subset of the plurality of expected beam transmissiondirections before the discovery period. In some embodiments, wherein thetransceiver is further configured to transmit a first channelreservation signal in the first subset of the plurality of expected beamtransmission directions based on the monitoring in the first subset ofthe plurality of expected beam transmission directions; and transmit asecond channel reservation signal in the second subset of the pluralityof expected beam transmission directions based on the monitoring in thesecond subset of the plurality of expected beam transmission directions.In some embodiments, wherein the channel is monitored in the firstsubset of the plurality of expected beam transmission directions withinthe discovery period before transmitting the subset of the plurality ofdiscovery signals. In some embodiments, wherein the transceiver isfurther configured to transmit a channel reservation signal in the firstsubset of the plurality of expected beam transmission directions beforetransmitting the subset of the plurality of discovery signals based onthe monitoring in first subset of the plurality of expected beamtransmission directions. In some embodiments, wherein the transceiver isfurther configured to transmit a channel reservation signal concurrentwith one of the subset of the plurality of discovery signals based onfrequency-division multiplexing (FDM). In some embodiments, wherein theprocessor is further configured to sense the channel by monitoring thechannel in a second subset of the plurality of expected beamtransmission directions within the discovery period; and detecting atransmission from another wireless communication device over the channelin the second subset of the plurality of expected beam transmissiondirections; and refrain from transmitting discovery signals in thesecond subset of the plurality of expected beam transmission directionsbased on the detecting. In some embodiments, wherein the transceiver isfurther configured to transmit a data signal by multiplexing the datasignal with one or more of the subset of the plurality of discoverysignals in at least one of a frequency domain or a time domain. In someembodiments, wherein the data signal is transmitted in at least one ofthe first subset of the plurality of expected beam transmissiondirections. In some embodiments, wherein each of the plurality ofdiscovery signals includes at least one of a primary synchronizationsignal (PSS), a secondary synchronization signal (SSS), a physicalbroadcast channel (PBCH) signal, or a discovery reference signal.

Further embodiments of the present disclosure include acomputer-readable medium having program code recorded thereon, theprogram code comprising code for causing a wireless communication deviceto sense a channel in a spatial domain based on a plurality of expectedbeam transmission directions, wherein the wireless communication deviceis associated with a first network operating entity, and wherein thechannel is shared by a plurality of network operating entities includingthe first network operating entity; and code for causing the wirelesscommunication device to transmit a plurality of discovery signals in oneor more of the plurality of expected beam transmission directions duringa discovery period to facilitate synchronization in the channel based onthe sensing.

In some embodiments, wherein the code for causing the wirelesscommunication device to sense the channel is further configured tomonitor the channel for a transmission from another wirelesscommunication device using an omnidirectional reception beam before thediscovery period. In some embodiments, the computer-readable mediumfurther comprises code for causing the wireless communication device totransmit a channel reservation signal using an omnidirectionaltransmission beam before the discovery period based on the sensing. Insome embodiments, wherein the code for causing the wirelesscommunication device to sense the channel is further configured tomonitor the channel in a first subset of the plurality of expected beamtransmission directions for a transmission from another wirelesscommunication device. In some embodiments, wherein the code for causingthe wireless communication device to monitor the channel is furtherconfigured to configure antenna elements of the wireless communicationdevice to direct reception in a beam direction including a coverage overthe first subset of the plurality of expected beam transmissiondirections. In some embodiments, wherein the code for causing thewireless communication device to transmit the plurality of discoverysignals is further configured to transmit, a subset of the plurality ofdiscovery signals, each in one of the first subset of the plurality ofexpected beam transmission directions. In some embodiments, wherein thecode for causing the wireless communication device to sense the channelis further configured to monitor the channel in a second subset of theplurality of expected beam transmission directions for a transmissionfrom another wireless communication device, wherein the first subset andthe second subset of the plurality of expected beam transmissiondirections are different, and wherein the channel is monitored in thefirst subset of the plurality of expected beam transmission directionsand in the second subset of the plurality of expected beam transmissiondirections before the discovery period. In some embodiments, thecomputer-readable medium further comprises code for causing the wirelesscommunication device to transmit a first channel reservation signal inthe first subset of the plurality of expected beam transmissiondirections based on the monitoring in the first subset of the pluralityof expected beam transmission directions; and code for causing thewireless communication device to transmit a second channel reservationsignal in the second subset of the plurality of expected beamtransmission directions based on the monitoring in the second subset ofthe plurality of expected beam transmission directions. In someembodiments, wherein the channel is monitored in the first subset of theplurality of expected beam transmission directions within the discoveryperiod before transmitting the subset of the plurality of discoverysignals. In some embodiments, the computer-readable medium furthercomprises code for causing the wireless communication device to transmita channel reservation signal in the first subset of the plurality ofexpected beam transmission directions before transmitting the subset ofthe plurality of discovery signals based on the monitoring in firstsubset of the plurality of expected beam transmission directions. Insome embodiments, the computer-readable medium further comprises codefor causing the wireless communication device to transmit a channelreservation signal concurrent with one of the subset of the plurality ofdiscovery signals based on frequency-division multiplexing (FDM). Insome embodiments, wherein the code for causing the wirelesscommunication device to sense the channel is further configured tomonitor the channel in a second subset of the plurality of expected beamtransmission directions within the discovery period; and detect atransmission from another wireless communication device over the channelin the second subset of the plurality of expected beam transmissiondirections, and wherein the computer-readable medium further comprisescode for causing the wireless communication device to refrain fromtransmitting discovery signals in the second subset of the plurality ofexpected beam transmission directions based on the detecting. In someembodiments, the computer-readable medium further comprises code forcausing the wireless communication device to transmit a data signal bymultiplexing the data signal with one or more of the subset of theplurality of discovery signals in at least one of a frequency domain ora time domain. In some embodiments, wherein the data signal istransmitted in at least one of the first subset of the plurality ofexpected beam transmission directions. In some embodiments, wherein eachof the plurality of discovery signals includes at least one of a primarysynchronization signal (PSS), a secondary synchronization signal (SSS),a physical broadcast channel (PBCH) signal, or a discovery referencesignal.

Further embodiments of the present disclosure include an apparatuscomprising means for sensing a channel in a spatial domain based on aplurality of expected beam transmission directions, wherein theapparatus is associated with a first network operating entity, andwherein the channel is shared by a plurality of network operatingentities including the first network operating entity; and means fortransmitting a plurality of discovery signals in one or more of theplurality of expected beam transmission directions during a discoveryperiod to facilitate synchronization in the channel based on thesensing.

In some embodiments, wherein the means for sensing is further configuredto monitor the channel for a transmission from another wirelesscommunication device using an omnidirectional reception beam before thediscovery period. In some embodiments, the apparatus further comprisesmeans for transmitting a channel reservation signal using anomnidirectional transmission beam before the discovery period based onthe sensing. In some embodiments, wherein the means for sensing isfurther configured to monitor the channel in a first subset of theplurality of expected beam transmission directions for a transmissionfrom another wireless communication device. In some embodiments, whereinthe means for sensing is further configured to monitor the channel byconfiguring antenna elements of the wireless communication device todirect reception in a beam direction including a coverage over the firstsubset of the plurality of expected beam transmission directions. Insome embodiments, wherein the means for transmitting the plurality ofdiscovery signals is further configured to transmit, a subset of theplurality of discovery signals, each in one of the first subset of theplurality of expected beam transmission directions. In some embodiments,wherein the means for sensing is further configured to monitor thechannel in a second subset of the plurality of expected beamtransmission directions for a transmission from another wirelesscommunication device, wherein the first subset and the second subset ofthe plurality of expected beam transmission directions are different,and wherein the channel is monitored in the first subset of theplurality of expected beam transmission directions and in the secondsubset of the plurality of expected beam transmission directions beforethe discovery period. In some embodiments, the apparatus furthercomprises means for transmitting a first channel reservation signal inthe first subset of the plurality of expected beam transmissiondirections based on the monitoring in the first subset of the pluralityof expected beam transmission directions; and means for transmitting asecond channel reservation signal in the second subset of the pluralityof expected beam transmission directions based on the monitoring in thesecond subset of the plurality of expected beam transmission directions.In some embodiments, wherein the channel is monitored in the firstsubset of the plurality of expected beam transmission directions withinthe discovery period before transmitting the subset of the plurality ofdiscovery signals. In some embodiments, the apparatus further comprisesmeans for transmitting a channel reservation signal in the first subsetof the plurality of expected beam transmission directions beforetransmitting the subset of the plurality of discovery signals based onthe monitoring in first subset of the plurality of expected beamtransmission directions. In some embodiments, the apparatus furthercomprises means for transmitting a channel reservation signal concurrentwith one of the subset of the plurality of discovery signals based onfrequency-division multiplexing (FDM). In some embodiments, wherein themeans for sensing is further configured to monitor the channel in asecond subset of the plurality of expected beam transmission directionswithin the discovery period; and detect a transmission from anotherwireless communication device over the channel in the second subset ofthe plurality of expected beam transmission directions, and wherein theapparatus further comprises means for refraining from transmittingdiscovery signals in the second subset of the plurality of expected beamtransmission directions based on the detecting. In some embodiments, theapparatus further comprises means for transmitting a data signal bymultiplexing the data signal with one or more of the subset of theplurality of discovery signals in at least one of a frequency domain ora time domain. In some embodiments, wherein the data signal istransmitted in at least one of the first subset of the plurality ofexpected beam transmission directions. In some embodiments, wherein eachof the plurality of discovery signals includes at least one of a primarysynchronization signal (PSS), a secondary synchronization signal (SSS),a physical broadcast channel (PBCH) signal, or a discovery referencesignal.

The functions described herein may be implemented in hardware, softwareexecuted by a processor, firmware, or any combination thereof. Ifimplemented in software executed by a processor, the functions may bestored on or transmitted over as one or more instructions or code on acomputer-readable medium. Other examples and implementations are withinthe scope of the disclosure and appended claims. For example, due to thenature of software, functions described above can be implemented usingsoftware executed by a processor, hardware, firmware, hardwiring, orcombinations of any of these. Features implementing functions may alsobe physically located at various positions, including being distributedsuch that portions of functions are implemented at different physicallocations. Also, as used herein, including in the claims, “or” as usedin a list of items (for example, a list of items prefaced by a phrasesuch as “at least one of” or “one or more of”) indicates an inclusivelist such that, for example, a list of [at least one of A, B, or C]means A or B or C or AB or AC or BC or ABC (i.e., A and B and C).

As those of some skill in this art will by now appreciate and dependingon the particular application at hand, many modifications, substitutionsand variations can be made in and to the materials, apparatus,configurations and methods of use of the devices of the presentdisclosure without departing from the spirit and scope thereof. In lightof this, the scope of the present disclosure should not be limited tothat of the particular embodiments illustrated and described herein, asthey are merely by way of some examples thereof, but rather, should befully commensurate with that of the claims appended hereafter and theirfunctional equivalents.

What is claimed is:
 1. A method of wireless communication, comprising:sensing, by a wireless communication device, a channel in a spatialdomain based on a plurality of expected beam transmission directions,wherein the wireless communication device is associated with a firstnetwork operating entity, and wherein the channel is shared by aplurality of network operating entities including the first networkoperating entity, wherein the sensing includes sweeping through multipledirectional reception beams and listening to the channel in a directionof each of the multiple directional reception beams; transmitting, afterthe sensing, by the wireless communication device, a channel reservationsignal using an omnidirectional transmission beam based on the sensing;and transmitting, after the sensing, by the wireless communicationdevice, a plurality of discovery signals in one or more of the pluralityof expected beam transmission directions during a discovery period tofacilitate synchronization in the channel based on the sensing.